b336a53425 The filament, generally not more than 1 m in diameter, is usually a gold-coated quartz fiber. Basics of Interferometry, 2nd edition. P. ^ Burch, J.M. doi:10.1119/1.17656. C.; Giallorenzi, T. (1979). He could operate this interferometer in the open, on a high hilltop with no temperature control, yet still achieve readings of 1/10 fringe accuracy.. "Extreme-ultraviolet phase-shifting point-diffraction interferometer: A wave-front metrology tool with subangstrom reference-wave accuracy".
For example, one year before their famous experiment of 1887, Michelson and Morley (1886) performed a repeat of the Fizeau experiment of 1851, replacing Fizeau's setup with an even-reflection Sagnac interferometer of such high stability, that even placing a lighted match in the light path did not cause artifactual fringe displacement. In 1935, Gustaf Wilhelm Hammar disproved a theoretical challenge to special relativity that attempted to explain away the null results of MichelsonMorleytype experiments as being mere artifact of aether-dragging, using an odd-reflection Sagnac interferometer. A currently ongoing upgrade to Advanced LIGO will require several kilowatts of laser power, and scientists will need to contend with thermal distortion, frequency variation of the lasers, mirror displacement and thermally induced birefringence. doi:10.1117/12.560959. arXiv:1007.0574. Philadelphia: Saunders. pp.3638. (2002). "Phase measurements of a twisted nematic liquid crystal spatial light modulator with a common-path interferometer". (1886).